package com.hong610.common.encryp;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import java.security.InvalidKeyException;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;

/**
 * 非对称加密
 * Created by Hong on 2016/12/12.
 */
public class EncrypRSA {
    /**
     * 加密
     */
    protected byte[] encrypt(RSAPublicKey publicKey, byte[] srcBytes) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
        if (publicKey != null) {
            //Cipher负责完成加密或解密工作，基于RSA  
            Cipher cipher = Cipher.getInstance("RSA");
            //根据公钥，对Cipher对象进行初始化  
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            byte[] resultBytes = cipher.doFinal(srcBytes);
            return resultBytes;
        }
        return null;
    }

    /**
     * 解密
     */
    protected byte[] decrypt(RSAPrivateKey privateKey, byte[] srcBytes) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
        if (privateKey != null) {
            //Cipher负责完成加密或解密工作，基于RSA  
            Cipher cipher = Cipher.getInstance("RSA");
            //根据公钥，对Cipher对象进行初始化  
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            byte[] resultBytes = cipher.doFinal(srcBytes);
            return resultBytes;
        }
        return null;
    }

    public static void main(String[] args) throws NoSuchAlgorithmException, InvalidKeyException, NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException {
        EncrypRSA rsa = new EncrypRSA();
        String msg = "Hong";
        //KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象  
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
        //初始化密钥对生成器，密钥大小为1024位  
        keyPairGen.initialize(1024);
        //生成一个密钥对，保存在keyPair中  
        KeyPair keyPair = keyPairGen.generateKeyPair();
        //得到私钥  
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
        //得到公钥  
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        //用公钥加密
        byte[] srcBytes = msg.getBytes();
        byte[] resultBytes = rsa.encrypt(publicKey, srcBytes);

        //用私钥解密  
        byte[] decBytes = rsa.decrypt(privateKey, resultBytes);

        System.out.println("明文是:" + msg);
        System.out.println("加密后是:" + new String(resultBytes));
        System.out.println("解密后是:" + new String(decBytes));
    }
}
